1. Field of the Invention
The present invention relates to an electronic device having a recognition function for a handwritten mathematical formula.
2. Description of the Related Art
Conventionally, a small-sized electronic calculator (a scientific electronic calculator) capable of functional computation such as the trigonometric function has been known in the art and in wide use. In recent years, a more advanced graph function calculator has been put to practical use. Compared with the conventional scientific calculator, the graph function calculator can process far more kinds of functions and is improved in performance, for example, in computation speed. In addition to these, the graph function calculator can display an arbitrary function formula as a graph, and has a computation function based on programming.
Since the graph function calculator is sophisticated, it is necessary to enter various kinds of numbers, characters and signs, and the graph function calculator must have a large number of keys. Furthermore, in order to input mathematical formulas for functional computation, various keys have to be operated in predetermined order in accordance with a function.
For example, when a mathematical formula for a definite integral is input, the elements of the mathematical formula for the integral have to be input by use of keys in the order of: the integral sign “∫”→the sign “^” representing the upper-limit value of an integral interval→the upper-limit value “a”→the sign “_” representing the lower-limit value→the lower-limit value “b”→an integrand “f(x)”.
As can be seen from this, it is a very heavy burden for a user to remember all key input orders determined for various kinds of functions. Under the circumstances, a handwritten mathematical formula recognition device, which performs character recognition for a mathematical formula handwritten on a touch panel by a user and inputs the recognized formula, is proposed in Jpn. Pat. Appln. KOKAI Publication No. 2007-072718, for example.
Since the handwritten mathematical formula recognition device has to perform collate and recognition processing for every handwritten input number and sign based on an enormous amount of recognition database, the time required for the recognition process is inevitably long. In addition, if the positional relationships between handwritten characters and signs differ from what they should be, the handwritten characters and signs may not be correctly recognized as part of the mathematical formula the user wants to enter.